Carbon-doped nano zero-valent iron as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a method for regulating and controlling a nanoscale zero-valent iron shell structure to enhance the reaction activity of the nanoscale zero-valent iron shell structure. The carbon-doped nano zero-valent iron is of a core-shell structure; the carbon-doped nanoscale zero-valent iron comprises a nanoscale zero-valent iron core with carbon gradient doping and an iron carbide shell layer located on the surface of the nanoscale zero-valent iron core. By means of collision between grinding balls and material (Fe and C) particles, deformation and crushing of the ground material particles are achieved through friction force, shearing force, tension and the like, an oxidation shell layer of nanoscale zero-valent iron is broken, Fe < 0 > is exposed on the surface of the material and further doped with activated carbon to form an iron carbide shell layer to construct Fe-C double-active sites, the reaction activity of the material is improved, and the service life of the material is prolonged. The reducibility and electron transfer capability of the nZVI are effectively improved, meanwhile, after the nZVI is subjected to the action of mechanical force, the lattice spacing of the nZVI is increased, the material property is changed, and the removal efficiency of the nZVI to pollutants is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a method for regulating the shell structure of nano zero-valent iron to enhance its reaction activity. Background Art

[0002] Nano-zero-valent iron (nZVI) has the advantages of high adsorption performance, strong reduction ability and high reactivity. It is often used for reduction degradation and adsorption and fixation of organic and inorganic pollutants, and has become an environmental pollution treatment material with great application prospects. At present, the most commonly used method for preparing nano-zero-valent iron in the laboratory is the liquid phase reduction method, which has significant advantages such as simple synthesis route, mild reaction conditions, easy equipment implementation, and the prepared nano-zero-valent iron has high purity and uniform particle size distribution. However, the liquid phase reduction method uses expensive chemical reduction reagents or uses high-energy electrochemical reactions, resulting in high preparation costs. In addition, many researchers have also developed preparation methods such as deep plastic deformation, physical vapor deposition, freeze drying, evaporation condensation, carbon thermal reduction and thermal decomposition, but most of the above methods require special equipment and high energy consumption, which are not suitable for the large-scale production of nano-zero-valent iron. At the same time, the surface of the "naked" zero-valent iron particles produced by the above methods is easily oxidized to form an iron oxide passivation layer, which greatly limits its wide application in the field of environmental remediation.

[0003] In order to overcome the above defects, surface modification (macromolecule polymer) or addition of loading materials (such as bentonite, kaolinite) is often used to disperse nano zero-valent iron particles to improve the dispersibility and stability of nano zero-valent iron particles, thereby improving the pollutant removal rate. However, the above methods cannot effectively solve the problem of reduced activity of nZVI due to surface shell passivation, and the organic reagents used in the preparation process of nZVI will cause secondary pollution to the environment.

[0004] Mechanical ball milling is a modification method that triggers surface chemical interactions through severe compression, shearing and impact, thereby producing a tight interfacial bonding connection between different raw materials. During the ball milling process, mechanical force can break the Fe-O bond of nZVI, thereby destroying the oxide passivation layer on its surface, exposing a fresh metal surface, and further improving its reactivity. However, simple ball milling of zero-valent iron can only break the oxide shell and temporarily increase the reactivity, but cannot fundamentally solve the problem of nZVI's easy oxidation and deactivation. In the prior art, micron-sized zero-valent iron and activated carbon are used as raw materials, and the modified iron-carbon material is obtained under mechanical forces such as friction, collision, and impact in a ball mill with a rotation speed of 300-500r / min under anaerobic conditions. However, since the weight ratio of activated carbon to zero-valent iron in the preparation process is 1:3-3:1, that is, the amount of activated carbon added is much greater than the mass of zero-valent iron, the modified iron-carbon material prepared is carbon-coated zero-valent iron, which covers the active sites on the surface of the material and reduces the reaction activity. Moreover, it is not mentioned that the prepared modified iron-carbon material can be used to degrade sulfamethoxazole. Therefore, it is necessary to further seek more effective methods to improve the antioxidant capacity and electron transfer efficiency of nZVI, so as to enhance the application effect of nZVI in environmental remediation. Summary of the invention

[0005] The purpose of the present invention is to provide a carbon-doped nano zero-valent iron and a preparation method and application thereof, so as to overcome the shortcomings of the prior art. Carbon-doped nano zero-valent iron is prepared by mechanical ball milling. By changing the shell structure of nZVI, the reducibility and electron transfer efficiency of nano zero-valent iron are improved, thereby achieving efficient removal of organic pollutants.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, the present invention provides a carbon-doped nano zero-valent iron, wherein the carbon-doped nano zero-valent iron has a core-shell structure; the carbon-doped nano zero-valent iron comprises a nano zero-valent iron core and an iron carbide shell layer, wherein the nano zero-valent iron core is a nano zero-valent iron doped with carbon active sites;

[0008] The iron carbide shell layer has Fe-C dual active sites; the Fe-C dual active sites are formed by doping carbon elements into the iron lattice.

[0009] In some other embodiments, the carbon is activated carbon, and the particle size of the activated carbon is 20-50 mesh;

[0010] The particle size of zero-valent iron is 400 meshes, and the purity is above 99.9%; the zero-valent iron can be purchased commercially or synthesized by existing methods. Compared with nano zero-valent iron, activated carbon particles are more "brittle" and the particles formed by long-term ball milling are smaller. The chemical bonding between activated carbon and nano zero-valent iron will be caused by mechanical force.

[0011] The overall inventive concept adopted by the present invention is:

[0012] In order to solve the problem that nano zero-valent iron (nZVI) is easily oxidized to produce an oxidized shell, which leads to a decrease in reaction activity, solid-solid ball milling technology is used as a breakthrough direction. The collision between the grinding balls and the material (Fe and C) particles is used to deform and break the grinding material particles through friction, shear force and tension, break the oxidized shell of nano zero-valent iron, and make Fe 0 Exposed on the surface of the material, and then further doped with activated carbon to form an iron carbide shell to construct Fe-C dual active sites, thereby improving the reactivity of the material. Compared with nZVI, the ball-milled iron-carbon composite nanomaterial can effectively improve the reducibility, pH range and electron transfer capacity of nZVI under the action of the Fe-C dual active sites. At the same time, after the mechanical force is applied to nZVI, its lattice spacing becomes larger, the material properties change, and the surface lattice, functional groups and other properties of zero-valent iron change.

[0013] In a second aspect, the present invention provides a method for preparing the carbon-doped nano zero-valent iron according to the first aspect, comprising the following steps:

[0014] Zero-valent iron and activated carbon are used as raw materials. The raw materials are ball-milled in an inert atmosphere by a forward-reverse alternating ball milling method to obtain carbon-doped nano-zero-valent iron, which is then washed, freeze-dried and stored for later use.

[0015] In some other embodiments, the mass ratio of zero-valent iron to activated carbon is (10-7): (0-3); the inert atmosphere is nitrogen or argon.

[0016] Preferably, the mass ratio of the zero-valent iron to the activated carbon is 9:1.

[0017] In some other embodiments, the ball milling process is as follows: the mass ratio of raw material to ball milling beads is 1:3-1:5, the ball milling speed is 200-500 rpm, the ball milling time is 2-30 h, and the forward and reverse alternating operation time is 0.5-1 h.

[0018] In some other embodiments, after the ball milling treatment is completed and before washing, the process further includes standing, and the standing time is 2-12 hours;

[0019] The washing solvent is ethanol or acetone;

[0020] The freeze-drying temperature is -20 to -40°C and the time is 10 to 15 hours;

[0021] The storage condition is vacuum or inert atmosphere.

[0022] In a third aspect, the present invention provides an application of the carbon-doped nano zero-valent iron described in the first aspect in degrading wastewater pollutants, wherein the pollutants are antibiotics, and preferably, the antibiotics are sulfamethoxazole.

[0023] In a fourth aspect, the present invention provides a method for degrading sulfamethoxazole, wherein peroxymonosulfate and the carbon-doped nano zero-valent iron described in the first aspect are added to wastewater containing sulfamethoxazole to carry out a degradation reaction.

[0024] In some other embodiments, the peroxymonosulfate is one of ammonium persulfate, potassium persulfate, potassium hydrogen persulfate and sodium persulfate;

[0025] In the wastewater, the concentration of sulfamethoxazole is 10-50 mg / L; the concentration of peroxymonosulfate is 10-50 mg / L; and the concentration of carbon-doped nano zero-valent iron is 0.1-1.0 g / L.

[0026] In some other embodiments, the degradation reaction temperature is room temperature and the time is 10-360 min.

[0027] Beneficial effects of the present invention:

[0028] (1) The present invention uses a ball mill device to construct an iron / carbon composite system to prepare a carbon-doped nano zero-valent iron composite material. The raw materials used are cheap and easily available, the preparation process is simple, there are no special requirements for external environmental conditions, and there is no secondary pollution.

[0029] (2) The carbon-doped nano zero-valent iron material prepared by the present invention has both the excellent electron transfer ability of the carbon material itself and the strong reduction performance of nZVI itself, which can effectively improve the reduction performance of nano iron particles and maintain a high electron transfer efficiency for a long time.

[0030] (3) The carbon-doped nano zero-valent iron material prepared by the present invention can still maintain a high reduction performance after aging in an air environment for one month. Through its unique Fe-C dual active sites, it can achieve the purpose of efficient reduction and catalytic oxidation degradation of halogenated pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0032] Figure 1 The SEM images of nano-zero-valent iron and carbon-doped nano-zero-valent iron in Example 1 of the present invention, wherein A is nano-zero-valent iron and B is carbon-doped nano-zero-valent iron, and the scale bars are both 1 μm;

[0033] Figure 2This is a high-resolution transmission electron microscopy image of carbon-doped nano zero-valent iron prepared in Example 1 of the present invention;

[0034] Figure 3 The XRD diagrams of activated carbon, nano zero-valent iron and carbon-doped nano zero-valent iron in Example 1 of the present invention are shown;

[0035] Figure 4 XRD diagrams of nano zero-valent iron, carbon-doped nano zero-valent iron and zero-valent iron before ball milling on the Fe(110) crystal plane in Example 1 of the present invention;

[0036] Figure 5 The XPS graphs of nano zero-valent iron and carbon-doped nano zero-valent iron in Example 1 of the present invention;

[0037] Figure 6 This is a reaction rate diagram of reduction degradation of sulfamethoxazole pollutants by nano-zero-valent iron and carbon-doped nano-zero-valent iron after aging in air for one month in Example 1 of the present invention;

[0038] Figure 7 This is a graph showing the degradation efficiency of sulfamethoxazole pollutant by carbon-doped nano zero-valent iron prepared in Example 1 of the present invention under different concentrations of peroxymonosulfate for efficient catalysis;

[0039] Figure 8 This is a reaction diagram of the quenching experiment of carbon-doped nano zero-valent iron prepared in Example 1 of the present invention;

[0040] Fig. 9 1 is an EPR graph of nano-zero-valent iron and carbon-doped nano-zero-valent iron in Example 1 of the present invention;

[0041] Fig.10 This is the Tafel diagram of the carbon-doped nano zero-valent iron prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] The following is a detailed description of the embodiments of the present invention: The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters for which specific conditions are not specified in the following embodiments are generally based on conventional conditions.

[0043] The activated carbon and zero-valent iron materials used in the embodiments of the present invention are purchased from Shanghai MacLean Co., Ltd., wherein the purity of the zero-valent iron is above 99.9%.

[0044] The ball milling device of the embodiment of the present invention is a YXQM planetary ball mill, the raw materials are added to the ball milling tank, and then the synthesis is carried out under the protection of nitrogen. The glove box (manufacturer is Mikaelona) is filled with high-purity nitrogen (99.999%).

[0045] 1. Preparation of Carbon-doped Nano Zero-Valent Iron Materials

[0046] Example 1

[0047] The specific steps of carbon-doped nano zero-valent iron materials are as follows:

[0048] (1) 180 g of commercial zero-valent iron with a diameter of 400 mesh and 20 g of activated carbon with a particle size of 50 mesh were used as raw materials (the mass ratio of commercial zero-valent iron to activated carbon was 9:1). The raw materials and stainless steel ball milling beads were placed in a 500 ml ball milling jar, wherein the mass ratio of ball milling beads to raw materials was 1:3;

[0049] (2) Place the ball mill in a glove box (with high-purity nitrogen), exhaust the air in the ball mill, and place the raw materials in the ball mill under a nitrogen-protected atmosphere;

[0050] (3) Place the ball mill filled with nitrogen in a planetary ball mill and run it alternately in forward and reverse directions for 30 hours. The ball mill speed is 400 rpm and the interval between forward and reverse directions is 1 hour.

[0051] (4) After ball milling, the ball mill was left to stand for 12 h, and then the powder obtained by ball milling was centrifugally cleaned with anhydrous ethanol;

[0052] (5) The cleaned powder was placed in a freeze dryer at -30°C for 12 h to obtain carbon-doped nano-zero-valent iron, and the carbon-doped nano-zero-valent iron was stored in a vacuum drying oven.

[0053] Example 2

[0054] The difference from Example 1 is that in step (1), the mass ratio of commercial zero-valent iron to activated carbon is adjusted to 8:2, and the other preparation steps are the same as those in Example 1.

[0055] Example 3

[0056] The difference from Example 1 is that in step (1), the mass ratio of commercial zero-valent iron to activated carbon is adjusted to 7:3, and the other preparation steps are the same as those in Example 1.

[0057] Example 4

[0058] The difference from Example 1 is that in step (1), the mass ratio of raw materials to ball mill beads is adjusted from 1:3 to 1:5, and the other preparation steps are the same as those in Example 1.

[0059] Example 5

[0060] The difference from Example 1 is that in step (1), the particle size of the activated carbon is adjusted to 20 mesh, and the other preparation steps are the same as Example 1.

[0061] Example 6

[0062] The difference from Example 1 is that in step (3), the rotation speed of the ball mill was adjusted from 400 rpm to 200 rpm, and the other preparation steps were the same as Example 1.

[0063] Example 7

[0064] The difference from Example 1 is that in step (3), the rotation speed of the ball mill is adjusted from 400 rpm to 500 rpm, and the other preparation steps are the same as those in Example 1.

[0065] Example 8

[0066] The difference from Example 1 is that in step (3), the ball milling time is adjusted from 30 hours to 2 hours, and the other preparation steps are the same as Example 1.

[0067] Example 9

[0068] The difference from Example 1 is that in step (3), the ball milling time is adjusted from 30 h to 12 h, and the other preparation steps are the same as those in Example 1.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that in step (1), no activated carbon is added, that is, the mass ratio of commercial zero-valent iron and activated carbon is adjusted to 10:0, and the other preparation steps are the same as Example 1.

[0071] Comparative Example 2

[0072] The difference from Example 1 is that in step (1), the mass ratio of commercial zero-valent iron to activated carbon is adjusted to 3:7, and the other preparation steps are the same as those in Example 1.

[0073] Comparative Example 3

[0074] The difference from Example 1 is that in step (3), the alternating forward and reverse operation for 30 hours is adjusted to forward operation for 30 hours, and the other preparation steps are the same as in Example 1.

[0075] Comparative Example 4

[0076] Different from Example 1, in step (3), the raw material is ball-milled at a speed of 300 r / min and a ball-milling time of 3 h using a forward and reverse alternating ball milling method, the diameter of the grinding balls used in the ball mill is 3.0 mm, and the mass ratio of the balls used in the ball mill is 10:1, to prepare the ball-milled iron-carbon material. An alternating operation cycle of the forward and reverse alternating ball milling method is: after 20 minutes of forward ball milling, 20 minutes of reverse ball milling is performed; and then the next alternating operation cycle is continued according to the above alternating operation cycle.

[0077] 2. Performance Test

[0078] 1. The nano zero-valent iron and the carbon-doped nano zero-valent iron material prepared in Example 1 were tested by scanning electron microscope. The results are as follows: Figure 1 As shown, A is nano zero-valent iron and B is carbon-doped nano zero-valent iron. Figure 1 It can be seen that compared with nano zero-valent iron ( Figure 1 As shown in A), carbon-doped nano-zero-valent iron ( Figure 1 This is because during the long ball milling process, the high-energy collision and friction can make the contact between the nano-zero-valent iron and the activated carbon particles closer, thereby smoothing the surface of the nano-zero-valent iron.

[0079] 2. The carbon-doped nano zero-valent iron materials prepared in Example 1 were tested by high-resolution transmission electron microscopy. The results are as follows: Figure 2 As shown, after long-term ball milling, Fe3C bonds were formed on the surface of AC@nZVI, indicating that the carbon element broke the oxide shell and formed Fe-C with the iron element, further proving that the material is a carbon-doped material.

[0080] 3. The crystal structures of activated carbon, nano-zero-valent iron and carbon-doped nano-zero-valent iron prepared in Example 1 were determined by XRD (Rigaku Miniflex 600, Japan) in the range of 5-90°. The results are as follows: Figure 3 As shown, from the measurement range of 10-30°, it can be seen that the characteristic peak of activated carbon appears on the carbon-doped nano zero-valent iron, indicating that the activated carbon and nano zero-valent iron are successfully composited.

[0081] The Fe(110) crystal plane of the nano-zero-valent iron prepared in Comparative Example 1, the carbon-doped nano-zero-valent iron prepared in Example 1, and the nano-zero-valent iron before ball milling were measured by XRD. The results are as follows: Figure 4 As shown in the figure, the characteristic peaks of the nano zero-valent iron prepared in Comparative Example 1 and the carbon-doped nano zero-valent iron prepared in Example 1 on the Fe(110) crystal plane are both shifted to the left relative to the nano zero-valent iron before ball milling, indicating that ball milling and adding activated carbon can change the Fe 0 Lattice spacing.

[0082] 4. X-ray electron spectroscopy (XPS) was used to measure the surface component content of the nano zero-valent iron prepared in Comparative Example 1 and the carbon-doped nano zero-valent iron prepared in Example 1. The measurement results are as follows: Figure 5 As shown, the Fe peaks of the nano zero-valent iron prepared in Comparative Example 1 and the carbon-doped nano zero-valent iron prepared in Example 1 have different peak areas, indicating that nZVI and carbon-doped nano zero-valent iron have different surface compositions. This is because with the doping of carbon elements, the iron oxide shell on the surface of nZVI is broken, the iron carbide shell is formed, and the structural composition of the iron element changes.

[0083] 5. Reduction and removal performance of sulfamethoxazole pollutants

[0084] (1) The removal rates of sulfamethoxazole by the materials prepared in the examples of the present invention and the comparative examples are shown in Table 1. The method for removing sulfamethoxazole pollutants is to add the carbon-doped nano zero-valent iron and potassium persulfate prepared in the present invention to the wastewater containing sulfamethoxazole for degradation reaction. The concentration of sulfamethoxazole in the wastewater is 50 mg / L, the concentration of potassium persulfate is 50 mg / L, and the concentration of carbon-doped nano zero-valent iron is 1 g / L. The temperature of the degradation reaction is room temperature, the time is 360 min,

[0085] Table 1 Removal rate of sulfamethoxazole

[0086] Serial number Sulfamethoxazole removal rate Example 1 78.6％ Example 2 36.9％ Example 3 34.6％ Example 4 61.5％ Example 5 56.3％ Example 6 41.7％ Example 7 65.4％ Example 8 21.9％ Example 9 37.9％ Comparative Example 1 37.9％ Comparative Example 2 13.5％ Comparative Example 3 47.6％ Comparative Example 4 27.8％

[0087] As can be seen from Table 1, excess carbon material will wrap the iron particles during the ball milling process, forming a physical covering layer that hinders direct contact between iron and pollutants. After the iron is isolated by the carbon layer as the catalytic active center, the effective active surface area ratio of iron decreases, and the active species cannot be effectively released, resulting in a decrease in catalytic efficiency. The coarse activated carbon particles are difficult to fully crush during ball milling, and the bonding interface with iron is limited. The carbon-iron two-phase separation in the composite material is obvious, and the synergistic effect is weak. In addition, it is difficult to fully load AC and nZVI in a short time of ball milling, and it is impossible to form Fe-C dual active sites.

[0088] (2) Effect of aging of carbon-doped nano-zero-valent iron on the degradation efficiency of sulfamethoxazole

[0089] The nano zero-valent iron prepared in Comparative Example 1 and the carbon-doped nano zero-valent iron prepared in Example 1 were aged in air for one month and then added to the wastewater containing sulfamethoxazole with potassium persulfate for degradation reaction. The concentration of sulfamethoxazole in the wastewater was 50 mg / L, the concentration of potassium persulfate was 50 mg / L, and the concentration of carbon-doped nano zero-valent iron was 1 g / L. The temperature of the degradation reaction was room temperature and the time was 1200 min. The test results are as follows: Figure 6 As shown, carbon-doped nano-zero-valent iron exhibits high stability and reactivity compared with nano-zero-valent iron.

[0090] (3) Effect of the concentration of carbon-doped nano-zero-valent iron on the degradation efficiency of sulfamethoxazole

[0091] The activated carbon, nano zero-valent iron and carbon-doped nano zero-valent iron materials were set to different concentrations (0.1 g / L and 0.2 g / L) and activated with potassium persulfate (concentration of 50 mg / L) for 48 hours to remove sulfamethoxazole. The test results are as follows: Figure 7As shown in the figure, at different concentrations, carbon-doped nano-zero-valent iron has a higher removal effect than nZVI. This result shows that carbon-doped nano-zero-valent iron has a higher electron transfer efficiency under the action of the iron carbide shell.

[0092] (4) Quenching experiments of carbon-doped nano-zero-valent iron materials with different quenchers

[0093] The prepared carbon-doped nano zero-valent iron material was subjected to quenching experiments with different quenchers. The quenching experiment was carried out in a 40ml sample bottle. First, 40mg of iron-carbon composite nanomaterials were added to sample bottles containing different quenchers. Secondly, 40ml of 50mg / L sulfamethoxazole solution was added to each sample bottle. Finally, samples were taken at 10, 30, 60, 120, 180, 240, and 360min of reaction. (The experiment was carried out at room temperature, and three parallel groups were set up for each group of experiments)

[0094] The concentration of carbon-doped nano-zero-valent iron in the wastewater was 1 g / L, activated with potassium persulfate (PMS, concentration was 50 mg / L), and the quenchers used were methanol (MeOH), tert-butyl alcohol (TBA), furfuryl alcohol (FFA), p-benzoquinone (PBQ), methyl phenyl sulfoxide (PMSO), trichlorohexamminecobalt (HMC) and sodium fluoride (NaF), and the amount of quencher added was 10 mM. The results are shown in Figure 2. Figure 8 As shown, furfuryl alcohol (FFA) and methyl phenyl sulfoxide (PMSO) played a major inhibitory role, indicating that the dominant active substances in the system are singlet oxygen and high-valent iron.

[0095] 6. EPR test of carbon-doped nano zero-valent iron materials

[0096] Carbon-doped nano zero-valent iron material was subjected to EPR testing. The test results are as follows Fig. 9 As shown in the figure, after adding activated carbon during ball milling, the free radical content in the iron-carbon composite material system increased. This is because the iron carbide shell on the surface of the iron-carbon composite material accelerated the efficiency of the zero-valent iron nucleus to transfer electrons to pollutants and peroxymonosulfate, resulting in an increase in the free radical content.

[0097] 7. Tafel test of carbon-doped nano zero-valent iron material

[0098] The prepared carbon-doped nano zero-valent iron material was subjected to a Tafel test. The Tafel test method is as follows: Tafel is performed in a three-electrode system in a 0.1 M Na2SO4 solution, and the scan is performed in the range of -1.0 to 1.0 V, with a scan rate of 0.01 V s -1 .

[0099] The test results are as follows Fig.10As shown, compared with nZVI, carbon-doped nano zero-valent iron has a higher self-corrosion potential and a lower self-corrosion current density, indicating that the iron-carbon composite material has stronger corrosion resistance and stable electron transfer ability.

[0100] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. A carbon-doped nano zero-valent iron, characterized in that: The carbon-doped nano zero-valent iron has a core-shell structure; the carbon-doped nano zero-valent iron comprises a nano zero-valent iron core and an iron carbide shell, and the nano zero-valent iron core is nano zero-valent iron doped with carbon active sites; The iron carbide shell layer has Fe-C dual active sites; the Fe-C dual active sites are formed by doping carbon elements into the iron lattice.

2. The carbon-doped nano zero-valent iron according to claim 1, characterized in that: The carbon is activated carbon, and the particle size of the activated carbon is 20-50 mesh; The particle size of zero-valent iron is 400 mesh and the purity is above 99.9%.

3. A method for preparing carbon-doped nano zero-valent iron according to claim 1 or 2, characterized in that: The following steps are involved: Zero-valent iron and activated carbon are used as raw materials. The raw materials are ball-milled in an inert atmosphere by a forward-reverse alternating ball milling method to obtain carbon-doped nano-zero-valent iron, which is then washed, freeze-dried and stored for later use.

4. The method for preparing carbon-doped nano zero-valent iron according to claim 3, characterized in that: The mass ratio of zero-valent iron to activated carbon is (10-7): (0-3); The inert atmosphere is nitrogen or argon Preferably, the mass ratio of the zero-valent iron to the activated carbon is 9:

1.

5. The method for preparing carbon-doped nano zero-valent iron according to claim 3, characterized in that: The ball milling treatment is as follows: the mass ratio of raw material to ball milling beads is 1:3-1:5, the ball milling speed is 200-500rpm, the ball milling time is 2-30h, and the forward and reverse alternating operation time is 0.5-1h.

6. The method for preparing carbon-doped nano zero-valent iron according to claim 3, characterized in that: After the ball milling treatment is completed and before washing, it also includes standing, and the standing time is 2-12 hours; The washing solvent is ethanol or acetone; The freeze-drying temperature is -20 to -40°C and the time is 10 to 15 hours; The storage condition is vacuum or inert atmosphere.

7. Use of the carbon-doped nano zero-valent iron according to claim 1 or 2 in degrading wastewater pollutants, wherein the pollutants are antibiotics, and preferably, the antibiotics are sulfamethoxazole.

8. A method for degrading sulfamethoxazole, characterized in that: Peroxymonosulfate and the carbon-doped nano zero-valent iron according to claim 1 or 2 are added to wastewater containing sulfamethoxazole to carry out a degradation reaction.

9. The method for degrading sulfamethoxazole according to claim 8, characterized in that: The peroxymonosulfate is one of ammonium persulfate, potassium persulfate, potassium hydrogen persulfate and sodium persulfate; In the wastewater, the concentration of sulfamethoxazole is 10-50 mg / L; the concentration of peroxymonosulfate is 10-50 mg / L; and the concentration of carbon-doped nano zero-valent iron is 0.1-1.0 g / L.

10. The method for degrading sulfamethoxazole according to claim 8, characterized in that: The temperature of the degradation reaction is room temperature and the time is 10-360 minutes.

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